屏幕保护有两个设置可选：默认为插入基座充电时
通过DreamBackend启用屏保，并且保存选择的时机
//QSSI.13\packages\apps\Settings\src\com\android\settings\dream\WhenToDreamPicker.java
@Override
protected boolean setDefaultKey(String key) {
mBackend.setWhenToDream(DreamSettings.getSettingFromPrefKey(key));
return true;
}
//QSSI.13\frameworks\base\packages\SettingsLib\src\com\android\settingslib\dream\DreamBackend.java
//启用屏保：
public void startDreaming() {
logd("startDreaming()");
if (mDreamManager == null) {
return;
}
try {
mDreamManager.dream();
} catch (RemoteException e) {
Log.w(TAG, "Failed to dream", e);
}
}
//记录启用时机
public void setWhenToDream(@WhenToDream int whenToDream) {
setEnabled(whenToDream != NEVER);
switch (whenToDream) {
case WHILE_CHARGING:
setActivatedOnDock(false);
setActivatedOnSleep(true);
break;
case WHILE_DOCKED:
setActivatedOnDock(true);
setActivatedOnSleep(false);
break;
case EITHER:
setActivatedOnDock(true);
setActivatedOnSleep(true);
break;
case NEVER:
default:
break;
}
}
public void setActivatedOnDock(boolean value) {
logd("setActivatedOnDock(%s)", value);
setBoolean(Settings.Secure.SCREENSAVER_ACTIVATE_ON_DOCK, value);
}
public void setActivatedOnSleep(boolean value) {
logd("setActivatedOnSleep(%s)", value);
setBoolean(Settings.Secure.SCREENSAVER_ACTIVATE_ON_SLEEP, value);
}
DreamBackend是对屏保管理的类，最终会通过IDreamManager来执行到DreamManagerService
启动屏保时，先获取系统安装的所有屏保，通过下列代码可以得到我们自己的开发的屏保
PackageManager pm = mContext.getPackageManager();
Intent dreamIntent = new Intent(DreamService.SERVICE_INTERFACE);
List
PackageManager.GET_META_DATA);
然后再将屏保设置我们自己开发的
//QSSI.13\frameworks\base\services\core\java\com\android\server\dreams\DreamManagerService.java
public void setActiveDream(ComponentName dream) {
logd("setActiveDream(%s)", dream);
if (mDreamManager == null)
return;
try {
ComponentName[] dreams = { dream };
mDreamManager.setDreamComponents(dream == null ? null : dreams);
} catch (RemoteException e) {
Log.w(TAG, "Failed to set active dream to " + dream, e);
}
}
如果没有设置，系统会有一个默认的屏保，使用以下方法可以获取默认屏保
//QSSI.13\frameworks\base\services\core\java\com\android\server\dreams\DreamManagerService.java
public ComponentName getDefaultDream() {
if (mDreamManager == null)
return null;
try {
return m